I have a 07 coupe not a limited and was told by my audio tech that i cannot change the head unit when I put the new subwoofer in and keep the stock speakers because they will not work I was going to have a 10 inch sub put in with a new headunit with the i pod plug. The tech said he could put the sub or the head unit in but not both without changing the speakers and going into the 2000$ range..all beacuse of Mercedes special amps that only work with factory speakers.If anyone was successful in putting in a sub and a head unit please let me know how you pulled it off for a reasonable price 0-1000$ I do not have Nav in my car

 

Find a new tech. I added a sub and head unit and it worked fine. I latter apgraded the door speakers for better sound.

 

So you have the base model?
The base model has no additional infinity amp, nor has the 6.5" subs in the rear.
It only has a 2 channel amp in the hu which is directly connected to speakers in the doors.
The hu is silver and has black *****, whereas the limited infinity hu has silver *****.

If you want to upgrade your system in a first step at a low price i would recommend to replace the hu, add a 4 channel amp (2 channels for the front system, 2 channels bridged for the sub) and a subwoofer with enclosure that you can put in the trunk. Also would recommend to dampen the doors with alubutyl and foam. If you want a better staging, than put new tweeters in the a pillow – but this will need to upgrade the front 2 way system, or run the system full active.

If you want to run your system full active (that means every speaker has his own amp) you'll need a hu with an active x-over (so you can divide the frequencies). Than you can use a 5 channel amp (1 channel for the sub, 2 channels for the 2 woofers in the door, 2 channels for the tweeters), or you can use the integrated amp of the hu for the tweeters and add a 4 channel amp. I would not recommend to run the door woofers over the hu amps, but that is also a possibility. In that configuration (run door woofers and tweeters over the integrated hu amps) you can use an sub with an integrated amp.

You see - there are many many many possibilities. Difference is cost and sound quality. Look for a good car hifi guy. Thell him what music you'll like and how much you want to spend. He should show you a lot of alternatives.

 

Thanks for the help.
I am going to go back to my stero guy; he is very very well respected in these parts and he was sure he could not upgrade my headunit to one with a i tune hookup and use my speakers.

All I want to do is add I podhookup and add a sub in my hatch...little bass thumping..I know I need a amp for bass but I wanted to keep all my other speakers stock for now He was saying that was not possiable because of stock amp and speakers,.

 

If you have a base model it should be no problem to update the hu with a ipod compatible.
Even if you have an infinity system that's no problem.

He should just replace the hu and use the internal amps of the hu.
The easiest way to add a subwoofer is to use a subwooferbox with an integrated amp that is powered by the sub chinch out of the hu. So the hu needs a sub chinch out with an integrated crossover. This is very common and even low to mid class hu's have that feature.

I've been using the stock speakers with another amp which had 70 watt RMS @ 4 ohm per channel for a little time withhout any problems. So the stock speakers can handle a little more power without problems.